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WO2011050097A1 - Système d'amélioration de la sensibilité - Google Patents

Système d'amélioration de la sensibilité Download PDF

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Publication number
WO2011050097A1
WO2011050097A1 PCT/US2010/053424 US2010053424W WO2011050097A1 WO 2011050097 A1 WO2011050097 A1 WO 2011050097A1 US 2010053424 W US2010053424 W US 2010053424W WO 2011050097 A1 WO2011050097 A1 WO 2011050097A1
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WIPO (PCT)
Prior art keywords
waveform
radar system
echoes
weather radar
bandwidth
Prior art date
Application number
PCT/US2010/053424
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English (en)
Inventor
Chandrasekaran Venkatachalam
Cuong Manh Nguyen
Nitin Bharadwaj
Original Assignee
Colorado State University Research Foundation
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Filing date
Publication date
Application filed by Colorado State University Research Foundation filed Critical Colorado State University Research Foundation
Publication of WO2011050097A1 publication Critical patent/WO2011050097A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/95—Radar or analogous systems specially adapted for specific applications for meteorological use
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/10—Systems for measuring distance only using transmission of interrupted, pulse modulated waves
    • G01S13/26—Systems for measuring distance only using transmission of interrupted, pulse modulated waves wherein the transmitted pulses use a frequency- or phase-modulated carrier wave
    • G01S13/28—Systems for measuring distance only using transmission of interrupted, pulse modulated waves wherein the transmitted pulses use a frequency- or phase-modulated carrier wave with time compression of received pulses
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/10—Systems for measuring distance only using transmission of interrupted, pulse modulated waves
    • G01S13/30—Systems for measuring distance only using transmission of interrupted, pulse modulated waves using more than one pulse per radar period
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G01S13/581—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of interrupted pulse modulated waves and based upon the Doppler effect resulting from movement of targets
    • G01S13/582—Velocity or trajectory determination systems; Sense-of-movement determination systems using transmission of interrupted pulse modulated waves and based upon the Doppler effect resulting from movement of targets adapted for simultaneous range and velocity measurements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/40—Means for monitoring or calibrating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Definitions

  • One of the fundamental objectives of meteorological radar systems is to sample the atmosphere surrounding the Earth to provide a quantitative measure of precipitation.
  • Conventional meteorological radars provide coverage over long ranges, often on the order of hundreds of kilometers.
  • a general schematic of how such conventional radar systems function is provided in Figure 1.
  • a radar is disposed at the peak of a raised geographical feature such as a hill or mountain 104.
  • the radar generates an electromagnetic beam 108 that disperses approximately linearly with distance, with the drawing showing how the width of the beam 108 thus increases with distance from the radar.
  • Various examples of weather patterns 1 16 that might exist and which the system 100 attempts to sample are shown in different positions above the surface 112 of the Earth.
  • Sensitivity is a critical aspect of weather radar systems. Such systems not only detect atmospheric patterns but often need to precisely measure weak precipitation echoes.
  • Embodiments of the invention use pulse compression techniques to increase the sensitivity of weather radar systems. These techniques can include sending two waveforms into a region of interest, where the second waveform is designed based on knowledge about the first waveform. Such systems can enhance the sensitivity of weather radars about 10 dB.
  • Embodiments of the invention include a weather radar system that includes a transmitter, a receiver and a computer system. The transmitter can be configured to transmit a first signal and a second signal into a region of interest. The receiver can be configured to receive first echoes and second echoes scattered from the region of interest.
  • the first echoes can correspond with the first transmitted signal and the second echoes can correspond with the second transmitted signal.
  • the computer system can be coupled at least with the receiver and can be configured to filter the second echoes based on information about either or both the first waveform and the first echoes.
  • the first and second waveforms comprise pulse compression waveforms.
  • the first waveform and the second waveform can be transmitted at the same time and in different in frequency.
  • the first waveform and the second waveform can be transmitted at different times and they are different in time.
  • the second waveform can be adaptively filtered based on information about the first waveform.
  • the second waveform can be filtered based on the power of the first waveform and/or the Doppler profiles of the first waveform.
  • an iterative loop can use the outputs of the second wave form as a reference profile to filter the second waveform itself.
  • a method for increasing the sensitivity of a radar system.
  • the method can include transmitting a first waveform into the atmosphere from a weather radar system and transmitting a second waveform, different from the first waveform, into the atmosphere from the weather radar system. Echoes can be received from the atmosphere in response to the first waveform and the second waveform. And the echoes of the second waveform can be filtered based on information about either or both the first waveform and the echoes from the first waveform.
  • Figure 1 provides a schematic illustration of the operation of a conventional radar system (reproduced from the National Academy of Sciences Report, "Flash flood forecasting over complex terrain”).
  • Figure 2 shows a simplified block diagram of a computational system that can be used to implement embodiments of the invention.
  • Figure 3 shows an illustration of the discrete signal model according to some embodiments of the invention.
  • Figure 4 shows an illustration of the shifted reference plane for reflectivity calculations according to some embodiments of the invention.
  • Figure 5A shows a time-based sensitivity enhancement scheme according to some embodiments.
  • Figure 5B shows a frequency-based sensitivity enhancement scheme according to some embodiments.
  • Figure 6A is a flow chart outlining a method for selecting the first and second waveforms according to some embodiments of the invention.
  • Figure 6B is a flow chart outlining a method for calculating the adaptive filter for the second waveform and an iteration loop to update the reference power profile.
  • Figure 7 is a flowchart outlining a checking procedure for two waveforms according to some embodiments of the invention.
  • Figure 8 shows a Gaussian shaped power profile of true power, SES power and MF power.
  • Figure 9A shows a graph of a trapezoid shape profile for both true and SES power according to some embodiments of the invention.
  • Figure 9B shows a graph of the bias and standard deviation of SES power according to some embodiments of the invention.
  • Figure 1 OA shows a graph of received reflectivity for both MF and SES according to some
  • Figure 1 OB shows a graph of the bias and standard deviation of SES power according to some embodiments of the invention.
  • Figure 1 1 A compares SNR profiles from MF and SES systems according to some embodiments of the invention.
  • Figure 1 IB shows the SNR difference between MF and SES shown in Figure 1 1A.
  • Figures 12A and 12B show the comparison of PPI data for true data, MF data and SES data using various embodiments described herein.
  • Figure 13 A shows an example of a first waveform according to some embodiments of the invention.
  • Figure 13B shows an envelope and normalized phase of the first waveform shown in Figure 13A.
  • Figure 14A shows an example of a second waveform according to some embodiments of the invention.
  • Figure 14B shows an envelope and normalized phase of the second waveform shown in Figure 13 A.
  • Sensitivity is a critical aspect of any radar system. It is especially important for weather radars because such systems not only detect atmospheric patterns but often need to precisely measure weak precipitation echoes.
  • pulse compression techniques for weather radars is not widely used, for low power systems it can be beneficial.
  • conventional matched or mismatched filters used along with pulse compression techniques have some constraints that partly downgrade the sensitivity.
  • Embodiments of the invention broadly termed sensitivity enhancement systems (SES), can obtain a better sensitivity than the other systems. For instance, SES with dual- waveforms scheme is able to enhance the sensitivity about 10 dB. It also provides good performance in PSL, Doppler tolerant and dual-polarization parameter estimation. For region with strong echoes, results by the two waveforms can be combined to improve measurement accuracy.
  • Pulse compression techniques are used through embodiments of the invention. Such systems transmit long coded waveforms by a weather radar into the atmosphere. The echoes are received and compression techniques are applied to narrow the pulses. Coded pulses can be useful because they require less power while maintaining increased bandwidth. Moreover, the range resolution and/or sensitivity of weather radars can be improved using these embodiments.
  • the increased bandwidth can have a major drawbacks: system noise. Because noise is proportional to bandwidth the increase in bandwidth can also increase the noise. With the increased noise, system sensitivity decreases. Moreover, the use of a low pass filter cannot be used in ground based weather radars to mitigate noise because the natural properties of the wideband echoes and white noise increase filter loss ruining any gains from the codes.
  • a two waveform scheme can be used. That is, two waveforms can be transmitted separately in either time and/or frequency. Then, at the receiver an adaptive filter can be designed based on the self consistency of these two waveforms. For example, the adaptive filter can filter the second waveform based on the first waveform and/or the echo from the first waveform. As another example, the adaptive filter can filter each range gate based on the prior knowledge of the power profile from the alternate waveform. Using embodiments of the invention can improve the system sensitivity and the peak sidelobe level (PSL) of the return echoes.
  • PSL peak sidelobe level
  • Figure 2 shows a simplified block diagram of a computer system 200 that can be coupled with a radar system that implements various embodiments of the invention.
  • Computer system 200 can be used to perform any or all the steps shown in Figure 6 and/or Figure 7.
  • computer system 200 can perform any or all the mathematical computations disclosed here.
  • the drawing illustrates how individual system elements can be implemented in a separated or more integrated manner.
  • the computer 200 is shown having hardware elements that are electrically coupled via bus 226.
  • Network interface 252 can communicatively couple the computational device 200 with another computer, for example, through a network such as the Internet.
  • the hardware elements can include a processor 202, an input device 204, an output device 206, a storage device 208, a computer-readable storage media reader 210a, a communications system 214, a processing acceleration unit 216 such as a DSP or special- purpose processor, and memory 218.
  • the computer-readable storage media reader 210a can be further connected to a computer-readable storage medium 210b, the combination comprehensively representing remote, local, fixed, and/or removable storage devices plus storage media for temporarily and/or more permanently containing computer-readable information.
  • Radar interface 250 is coupled with bus 226.
  • radar interface 250 can be any type of communication interface.
  • radar interface 250 can be a USB interface, UART interface, serial interface, parallel interface, etc.
  • Radar interface 250 can be configured to couple directly with any type of radar system such as a dual polarization radar system.
  • the computer system 200 also comprises software elements, shown as being currently located within working memory 220, including an operating system 224 and other code 222, such as a program designed to implement methods and/or processes described herein.
  • other code 222 can include software that provides instructions for receiving user input a dual polarization radar system and manipulating the data according to various embodiments disclosed herein.
  • other code 222 can include software that can predict or forecast weather events, and/or provide real time weather reporting and/or warnings. It will be apparent to those skilled in the art that substantial variations can be used in accordance with specific requirements. For example, customized hardware might also be used and/or particular elements might be implemented in hardware, software (including portable software, such as applets), or both. Further, connection to other computing devices such as network input/output devices can be employed.
  • a pulse compression radar system can have a chirp frequency of F s . The sampling time is then
  • T s — .
  • Figure 3 shows a signal transmission model where both precipitation range profile and transmitted waveforms are sampled at frequency F s .
  • w N _ l is the N-length vector of the sampled waveform
  • ISL integrated sidelobe level
  • PSL peak sidelobe level
  • the minimization process gives a closed form solution for the case of minimum ISL.
  • a minimum ISL filter provides sufficiently low PSL. This design can be suitable for the first waveform of SES, in some embodiments, where the need of PSL is more important than the achieved resolution.
  • the reflectivity is estimated from the received power at the shifted reference plane, as shown in Figure 4.
  • the reflectivity can be given by,
  • This analysis does not account for Doppler shift; i.e. it sets all Doppler shifts of samples (range gate volumes) to zeros.
  • radial Doppler of weather echoes is not as high as in case of military targets such as aircrafts it still affects the PSL performance of the receiver filter.
  • weather radar systems need to measure precipitation echoes accurately. A strong, moving fast storm may heavily contaminate nearby weak cells due to the sidelobe problem. Therefore, when designing system, the signal Doppler needs to be taken into account.
  • the Doppler phase shift over a period of Ts is .
  • the Doppler phase shift of the signal at gate (n+k)* has impact on the covariance matrix R yy .
  • Embodiments of the invention can employ a dual- waveform scheme.
  • Knowledge about the first signal can be used to derive a second signal that can provide increased sensitivity.
  • the knowledge about the signal that can be used by the SES estimator can include the signal power and the signal Doppler.
  • Figure 5 A shows a dual-waveform scheme where the first waveform, Bi, is separated in time from waveform B 2 .
  • Figure 5B shows a dual-waveform scheme where the first waveform, Bi, is separated in frequency from waveform B 2 .
  • the two waveforms can be separated in both time an frequency.
  • the observed volume can be perfectly matched. If the two waveforms are transmitted at different times, the time difference can be selected to be small enough to ensure that the precipitation volume is statistically stationary. For example, when the two waveforms are transmitted in a sequence, as shown in Figure 5A; the difference in transmission time between the two waveforms can be equal to the integration time for the first waveform. This can be of the order of ms. With that time apart, precipitation targets can be assumed to be unchanged.
  • the first waveform can be used to estimate detailed knowledge about the signal while the second waveform can be used to utilize that information to improve the system sensitivity.
  • the second waveform for example, can be designed with native resolution (i.e. inverse of the bandwidth) smaller than the practical resolution of the first waveform. By choosing adequate waveforms, embodiments of the invention can improve the system sensitivity efficiently.
  • the second waveform estimator can use some information about the signal of interest.
  • the SES filter can be adaptive to the signal level. That matching property can be important since it always provides better signal to noise ratio (SNR).
  • SNR signal to noise ratio
  • the conventional match filter when applied to weather radar is not really the match filter since precipitation targets are volume targets, received signal is not a time-frequency shifted version of the transmitted waveform.
  • the SES waveforms can be designed to transmit in time or in frequency domain.
  • the two waveforms can be selected to transmit after each other in time.
  • both waveforms can use the whole available system bandwidth.
  • the two waveforms can be located at different frequencies within that band. Volume matching in this case can be good and/or dwell time can be reduced by half compared to the first case.
  • Figure 6 is a flow chart outlining a method for selecting the first and second waveforms.
  • the selection of waveform parameters described below is example only. Various system specification and/or requirements can change these parameters; for example, the transmitter duty circle.
  • the frequency and/or bandwidth of the first and second waveforms are chosen. In some embodiments, the bandwidth of the second waveform can be selected to be two to four times less than the bandwidth of the first waveform.
  • the duration of the waveforms is determined. In some embodiments, the first waveform duration can be set to be equal to or longer than the second waveform. Again, the selection depends on system specifications and/or design domains (e.g. waveforms can have either or both time diversity or frequency diversity).
  • the second waveform filter can require N 2 samples before and after the wanted gate (where N 2 is the number of chirps within the second waveform). Increasing the length of the second waveform (N 2 ) can lessen the number of gate where the filter can be applied.
  • the first waveform can be designed using any advanced method.
  • the goal is to obtain the best performance in terms of resolution and PSL. This can be done by assigning pulse codes to the first waveform using any known pulse compression technique.
  • the range resolution of the first waveform can be computed from the effective bandwidth of the impulse response of the first waveform.
  • the second waveform bandwidth can be determined. For example, it can be selected such as the corresponding range resolution (i.e. inverse of the bandwidth) is a multiple of the first waveform resolution (as calculated in block 615). Depending on the requirement of the final resolution; the multiplication factor can be selected appropriately.
  • the second waveform duration can be determined at block 630.
  • the second waveform can be designed.
  • Figure 6B is a flow chart outlining a method for calculating the adaptive filter for the second waveform according to some embodiments of the invention. This can be used to update the reference power profile.
  • the signal power profile and Doppler profile can be estimated from the first waveform using an ISL filter.
  • the first waveform can be filtered using an ISL filter at block 650. From this filtered data, the signal power profile and/or the Doppler profile can be computed at block 655. These profiles can then be used as inputs to compute filter coefficients for the second waveform. That is, an adaptive filter can be computed for the second waveform at each range gate at block 660. This adaptive filter can then be used to filter the second waveform. To further improve the sensitivity of the system, an iteration loop can be introduced. Outputs of the second waveform can be used as reference profiles of the filter design phase for the second waveform itself at block 670. Using an iteration loop can help increases the estimated standard deviation and/or possibly reduces the number of range gates where the filter can be applied.
  • the second waveform's output has higher sensitivity.
  • the two waveform estimates are usually good; one may combine them to lower measurement errors. For example, this can be accomplished by taking the average of both products.
  • an SES estimator can use the signal power as prior knowledge but its output may not converge to the true power.
  • a checking procedure based on the likelihood test can be used. The likelihood functions of two signal distributions can be compared: one with the first waveform power estimate and the other with the SES power from the second waveform.
  • Figure 7 shows a flowchart outlining this procedure.
  • the signal powers for both waveforms can be estimated.
  • the sample covariance matrix of the signal can be calculated for the second waveform along range:
  • the negative log-likelihood function values can be compared with power estimates from both waveforms. Powers that provide smaller value will be chosen.
  • L n TM"- l ⁇ de ⁇ R ⁇ )) + trace(R B raBge R J , J , "1 ) where R yy is shown above and p réelle is replaced by the two estimated powers.
  • power estimates corresponding to the log-likelihood function can be selected.
  • Some embodiments of the invention can be verified using pulse compression simulation data. For example, input profiles for the simulation are simulated precipitation range profiles and based on actual measurements from Collaborative Adaptive Sensing of the Atmosphere Integrative Project 1 (CASA IP 1). The simulation was done with the impact of Doppler included. Simulation input parameters are listed in the Table 1. The waveforms used in this simulation are shown in Figures 13 and 14.
  • a match filter was also applied to the simulation data for comparison purposes.
  • signals from a MF system are averaged in range to have the same resolution as provided by the SES.
  • a precipitation range profile is simulated as the sum of two Gaussian shaped echoes. The echo with narrow width is similar to an impulse while the second echo shows a high gradient in power.
  • Figure 8 shows the output of a match filter (MF) for the both waveforms.
  • Output from a match filter for the second waveform has relatively good sensitivity but is bad in terms of resolution and/or PSL, as expected for a waveform with the pulse compression ratio (BT) of only 33. Therefore, from this point, SES is compared to the MF output at the first waveform.
  • Figure 8 also shows that the SES can detect a weaker signal than the MF system.
  • the SES has PSL larger than 60 dB even at Doppler velocity of 25 m/s. These simulation results show about 8 dB improvement in sensitivity. If noise subtraction is applied, then a SES shows about 10 dB of improvement.
  • SES can improve sensitivity by introducing an iterative procedure to update the reference profiles of SES.
  • Figure 1 OA a the received reflectivity profiles for MF and SES of a Cyril radar profile at azimuth of 330 deg is shown. And Figure 10B the bias and standard deviation of the Cyril radar profile are also shown.
  • Figure 1 1A shows the SNR profiles from MF and SES.
  • Figure 1 IB shows the SNR difference between the two.
  • FIGs 12A and 12B PPI data from Cyril radar are used as the input for the SES simulation.
  • the averaged transmitted power for the SES is 100W and for MF system is 700 W.
  • Signal 14 spectral moments and dual-polarization parameters are estimated using a standard method with noise subtraction.
  • the SES with 100W transmitted power provides results comparable to the ones from MF system with 700W transmitted power. Therefore, in this case, the gain in sensitivity is about 7 times or 8.45 dB.
  • programmable processor can be configured by providing suitable executable code; a dedicated logic circuit can be configured by suitably connecting logic gates and other circuit elements; and so on.
  • Computer programs incorporating various features of the present invention may be encoded on various computer readable storage media; suitable media include magnetic disk or tape, optical storage media such as compact disk (CD) or digital versatile disk (DVD), flash memory, and the like.
  • Computer readable storage media encoded with the program code may be packaged with a compatible device or provided separately from other devices.
  • program code may be encoded and transmitted via wired optical, and/or wireless networks conforming to a variety of protocols, including the Internet, thereby allowing distribution, e.g., via Internet download.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

La présente invention porte sur la sensibilité comme un aspect essentiel des systèmes de radars météorologiques. De tels systèmes non seulement détectent les tendances atmosphériques mais encore doivent souvent mesurer avec précision des échos de précipitation faibles. Des modes de réalisation de l'invention utilisent des techniques de compression d'impulsions pour augmenter la sensibilité des systèmes de radars météorologiques. Ces techniques peuvent comprendre l'envoi de deux formes d'onde dans une région d'intérêt, la seconde forme d'onde ayant été conçue sur la base des connaissances concernant la première forme d'onde. De tels systèmes peuvent améliorer la sensibilité des radars météorologiques d'environ 10 dB.
PCT/US2010/053424 2009-10-20 2010-10-20 Système d'amélioration de la sensibilité WO2011050097A1 (fr)

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US25337109P 2009-10-20 2009-10-20
US61/253,407 2009-10-20
US61/253,371 2009-10-20
US12/908,657 2010-10-20
US12/908,657 US8274423B2 (en) 2009-10-20 2010-10-20 Sensitivity enhancement system

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